Last changed: 26.8.2026.
The data controller is Vladan Pejović, Kraljevo, Srbija, Republic of Serbia. Contact for privacy questions: privacy@chesstrainers.app.
Chess Brain Trainer requires no account, shows no advertising, and collects no personal data such as your name, email address or contacts. There is nothing to sign in to and nothing to sign out of.
Everything the app records about your practice — puzzles played, results, XP, ranks, achievements and settings — is stored only on your device. It never leaves it, we never see it, and it is deleted when you uninstall the app.
The app uses Firebase Crashlytics (Google). What it sends:
It does not contain your name, email address or anything you typed. Reports are sent over an encrypted connection and are deleted automatically after 90 days.
They are used to find and fix faults, and — in aggregate, across all installations — to see how the app performs and where it fails most often. That second use is why Analytics appears as a purpose in the Data safety section of the Play listing.
This reporting is active in every released version and there is currently no switch in the app to turn it off. It is off in development builds only.
The optional Premium purchase is processed by Google Play. Google is the seller and handles your payment — we never receive and never store a card number or any payment detail.
You can delete everything the app has recorded about you at any time by uninstalling it — that data is on your device and nowhere else.
For crash reports and diagnostics, which are the only data that leaves your device, you may ask what is held, ask for it to be deleted, or object to the processing, by writing to privacy@chesstrainers.app. We answer within 30 days. Please say roughly when the crash happened and on which device, because a report carries no name to search by.
If you believe your rights have been infringed, you may address the Commissioner for Information of Public Importance and Personal Data Protection of the Republic of Serbia.
The app is suitable for all ages. It shows no advertising, asks for nothing about the person using it, and links to no external content. It is not directed at children specifically, and it collects no more from a young user than from anybody else — which is nothing beyond the crash reports above.
If we change this policy, the new version appears at this same address and the date at the top changes.
Vladan Pejović
Kraljevo, Srbija
privacy@chesstrainers.app